Propagating metadata associated with digital video

ABSTRACT

Some embodiments provide a method for processing metadata associated with digital video in a multi-state video computer readable medium. The method specifies a set of rules for propagating the metadata between different states in the video computer readable medium. It then propagates the metadata between the states based on the specified set of rules.

FIELD OF THE INVENTION

The present invention is directed towards propagating metadata associated with digital video.

BACKGROUND OF THE INVENTION

When first designed, the digital video format was truly revolutionary, not only in its treatment of the storage of video/audio media, but also in the transport used to move media between devices. With a digital tape format, timecode was no longer relegated to special purpose control tracks, but carried along with the relevant video and audio data in a cohesive frame based unit. A pure digital connection (e.g., a connection over SDI or FireWire) allows for data to be transferred between devices with no information loss. Beyond simple timecode, extra space is set aside in each frame to carry other types of useful embedded “metadata”, including such information as camera configuration/exposure settings, time of day, scene breaks, etc.

In many modern non-linear editors (NLE's), most of this auxiliary information is ignored. Moreover, there does not exist a coherent approach for propagating metadata across different stages of the editing pipeline. Therefore, there is a need in the art for an innovative method for propagating metadata across different stages of a video processing system. Ideally, this method should allow an editor to provide different rules for propagating different types of metadata.

SUMMARY OF THE INVENTION

Some embodiments provide a method for processing metadata associated with digital video in a multi-state video processing system. The method specifies a set of rules for propagating the metadata between different states in the video processing system. It then propagates the metadata between the states based on the specified set of rules.

For instance, in some embodiments, the method exports digital video to a storage. This method initially determines whether a set of metadata of the digital video has an associated set of rules for exporting the set of metadata. If so, it then exports the set of metadata to the storage based on the set of rules.

In some embodiments, the method recaptures digital video from a first storage, when at least a portion of the digital video is also stored in a second storage. The method retrieves the digital video from the first storage. It identifies a set of metadata that is stored for the digital video in the second storage, and then determines whether there is an associated set of rules for processing this set of metadata when the digital video is re-captured from the first storage. If so, the method then stores the set of metadata with the retrieved digital video in a third storage.

In some embodiments, the method displays metadata associated with digital video. The method retrieves a set of metadata associated with the digital video. It then determines whether the set of metadata has an associated set of rules for displaying the set of metadata. If the set of metadata has such a set of associated rules, the method displays the set of metadata according to the set of associated rules.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appended claims. However, for purpose of explanation, several embodiments of the invention are set forth in the following figures.

FIG. 1 illustrates the conceptual attributes of a metadata set in some embodiments.

FIG. 2 illustrates one manner for defining a metadata set with an implicit duration in an OS X® environment of Apple Computers, Inc.

FIG. 3 illustrates one manner for defining a metadata set with an explicit duration in an OS X® environment of Apple Computers, Inc.

FIG. 4 conceptually illustrates a rule-specifying structure.

FIG. 5 illustrates a process that some embodiments use to export a digital video presentation from an application database of a video editing application to a file that is stored on a storage.

FIG. 6 illustrates a process that some embodiments use during the recapture of the audio or video components of a digital video presentation.

FIG. 7 illustrates a process that some embodiments use to display the metadata associated with a digital video presentation.

FIG. 8 conceptually illustrates a computer system that can be used to implement some embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous details are set forth for purpose of explanation. However, one of ordinary skill in the art will realize that the invention may be practiced without the use of these specific details. In other instances, well-known structures and devices are shown in block diagram form in order not to obscure the description of the invention with unnecessary detail.

Some embodiments provide a method that processes metadata associated with video in a multi-state video processing system. This method specifies a set of rules for propagating the metadata between different states in the video processing system. It then propagates the metadata between the states based on the specified set of rules.

For instance, in some embodiments, the method exports digital video to a storage. This method initially determines whether a set of metadata of the digital video has an associated set of rules for exporting the set of metadata. If so, it then exports the set of metadata to the storage based on the set of rules.

In some embodiments, the method recaptures digital video from a first storage, when at least a portion of the digital video is also stored in a second storage. The method retrieves the digital video from the first storage. It identifies a set of metadata that is stored for the digital video in the second storage, and then determines whether there is an associated set of rules for processing this set of metadata when the digital video is re-captured from the first storage. If so, the method then stores the set of metadata with the retrieved digital video in a third storage.

In some embodiments, the method displays metadata associated with digital video. The method retrieves a set of metadata associated with the digital video. It then determines whether the set of metadata has an associated set of rules for displaying the set of metadata. If the set of metadata has such a set of associated rules, the method displays the set of metadata according to the set of associated rules.

The set of associated rules for a set of metadata can include only one rule, or it can include several rules. A metadata set's associated rule set can also include a rule specifying whether all or part of the metadata set should be exported, recaptured, or displayed. The default operation of some embodiments is to propagate a metadata set from one state to another when no set of associated rules exists for propagating the metadata set.

I. Metadata

Digital video metadata can include a variety of ancillary data, such as time of day, timecode, camera settings, encoding cadence, film maker's comments, etc. The metadata is specified and stored differently in different embodiments. FIG. 1 illustrates the conceptual attributes of each metadata set in some embodiments. As shown in this figure, each metadata set has a scope 105 that specifies the metadata set's associated portion of digital video. This portion can be an entire file, one or more tracks in the file, or a portion of one or more tracks in the file. The scope can be specified explicitly or implicitly for a metadata set.

As shown in FIG. 1, the metadata set includes metadata content 110, which is the actual metadata in the set. Also, the metadata set includes a temporal duration 115. Different embodiments define the temporal duration differently. For instance, this duration is implicit in some embodiments, while it is explicit in other embodiments.

FIG. 2 conceptually illustrates one manner for defining a metadata set with an implicit duration in an OS X® environment of Apple Computers, Inc. Specifically, this figure illustrates a user data element 200 that has (1) a 4-character index 205, which is associated with a particular audio/video item (e.g., a/v track or movie), and (2) a metadata container 210 that stores the metadata. The duration of such a data element is implicitly assumed to match the duration of the a/v item associated with the item (i.e., the a/v item associated with the character index 205).

FIG. 3 conceptually illustrates one manner for defining a metadata set with an explicit duration in an OS X® environment of Apple Computers, Inc. Specifically, this figure illustrates that some embodiments define a metadata set by defining a metadata track, giving the track specific start and end times, and associating the metadata track with one or more a/v tracks. In FIG. 3, the metadata track is track 305, which has start and end times 315 and 320, and which references a video track 310. In such embodiments, the actual metadata content is stored in the metadata track 305, and the duration of the metadata is derived from the specified start and end times and the sample times.

Some embodiments organize a metadata set (e.g., organize the metadata content that is stored in the metadata track 305 of FIG. 3 or the metadata container 210 of FIG. 2) in a rule-specifying structure that specifies one or more propagation rules for one or more metadata items in the metadata set. FIG. 4 conceptually illustrates one such rule-specifying structure. As shown in this figure, the rule-specifying structure 400 can specify several propagation rules for several propagation events for a metadata set. In some embodiments, the rule-specifying structure is an XML document that uses XML keys, codes and tags to specify different metadata items and rules for propagating these items.

II. Exporting Metadata

FIG. 5 illustrates a process 500 that some embodiments use to export a digital video presentation from an application database of a video editing application to a file (“destination file”) that is stored on a storage (e.g., a hard drive). This presentation has a video track that is a composite of one or more video tracks and/or special effects. It might also include an audio track that is a composite of one or more audio tracks and/or special effects. It also might include one or more sets of metadata. Each metadata set might include one or more metadata items (i.e., one or more subsets of metadata content). For instance, one metadata set might include the time. This metadata set's individual metadata items might be specified as the time of day, day, month, and year. Another metadata set might be the director's comments, and this set's individual metadata items might be the director's comments for each individual scene in the presentation.

As shown FIG. 5, the process initially stores (at 505) the video track of the presentation in the destination file. It then stores (at 510) the audio track of the presentation in the destination file. The process next determines (at 515) whether there is any metadata set associated with the a/v presentation. If not, the process ends.

Otherwise, the process selects (at 520) a metadata set. It then determines (at 525) whether the metadata set that it just selected at 520 includes any export rules regarding exporting the selected metadata set. If not, the process writes (at 530) the selected metadata set to the destination file, and then transitions to 545, which will be described below. Otherwise, the process determines (at 535) whether the export rule of the selected set prohibits exporting all metadata items in the selected metadata set. If so, the process transitions to 545, which will be described below.

On the other hand, if the export rule specifies that all or part of the metadata set should be exported, the process transitions to 540. At 540, the process writes the selected metadata set to the destination file according to the export rule identified at 525. In other words, at 540, the process writes to file the portion of the selected metadata set that this set's export rule designates for exporting. In some embodiments, the export rule for a metadata set can only specify whether the entire metadata set should be exported or not. Other embodiments, however, allow a metadata set's export rule to specify smaller portions of a metadata set for exporting. After 540, the process transitions to 545.

At 545, the process determines whether it has examined all metadata sets of the a/v presentation. If not, the process returns to 520 to select a metadata set of the presentation that it has not yet examined, and then repeats the above-described operations 525-545 for this selected set. When the process determines that it has examined all the metadata sets of the a/v presentation, it ends.

III. Regenerating Metadata

FIG. 6 illustrates a process 600 that some embodiments use during the recapture of the audio or video components of a digital video presentation. This presentation typically includes (1) a video track that is a composite of one or more video tracks and/or special effects, and (2) an audio track that is a composite of one or more audio tracks and/or special effects. It also might include one or more sets of metadata, each of which might include one or more metadata items.

In some embodiments, before the recapture operation, a video editing application's data storage includes some or all of the audio or video components plus metadata associated with these components. In some of these embodiments, the recapture operation imports from a first data storage (e.g., a tape or a file stored on disk) audio or video components of a digital video presentation into the application data storage of the video editing application. This recapture operation might be performed when the original a/v components in the application data storage are corrupted or are incomplete.

As shown FIG. 6, the process initially identifies (at 605) the time period in the a/v presentation for which it needs to recapture a/v data. From the first storage, it then (at 610) recaptures the a/v data within the period identified at 605 and stores the captured data in a media file (e.g., a file on disk). The process next determines (at 615) whether there is any metadata set in the application data storage (e.g., application database) that is associated with the portion of the a/v presentation that the process 600 is recapturing. If not, the process imports (at 650) the media file into the application database, and then ends. Some embodiments import a media file into the application data storage by simply linking the media file to the application data storage.

Otherwise, from the application data storage, the process selects (at 620) a metadata set that is associated with the portion of the a/v presentation that the process 600 is recapturing. It then determines (at 625) whether the metadata set that it just selected at 620 includes any recapture rules regarding processing the selected metadata set during a recapture operation. If not, the process writes (at 630) the selected metadata set to the media file, and then transitions to 645, which will be described below. Otherwise, the process determines (at 635) whether the recapture rule of the selected set prohibits the recapturing of all data in the selected metadata set. If the recapture rule prohibits the recapture of all data in the selected metadata set, the process transitions to 645, which will be described below.

On the other hand, if the recapture rule specifies that all or part of the metadata set should be recaptured, the process transitions to 640. At 640, the process writes the selected metadata set to the media file (that contains the a/v components that were recaptured at 610) according to the recapture rule identified at 625. In other words, at 640, the process writes to the media file the portion of the selected metadata set that this set's recapture rule designates for recapturing. In some embodiments, the recapture rule for a metadata set can only specify whether the entire metadata set should be recaptured or not. Other embodiments, however, allow a metadata set's recapture rule to specify smaller portions of a metadata set for recapturing. After 640, the process transitions to 645.

At 645, the process determines whether it has examined all metadata sets associated with the portion of the a/v presentation that the process 600 is recapturing. If not, the process returns to 620 to select another associated metadata set that it has not yet examined, and then repeats the above-described operations 625-645 for this selected set. The process transitions to 650 when the process determines (at 645) that it has examined all the metadata sets that are associated with the portion of the a/v presentation that the process 600 is recapturing. At 650, the process imports the media file into the application database, as mentioned above. Some embodiments import a media file into the application data storage by simply linking the media file to the application data storage. After 650, the process ends.

IV. Displaying Metadata

FIG. 7 illustrates a process 700 that some embodiments use to display the metadata associated with a digital video presentation. As with exporting and recapturing, the a/v presentation typically includes (1) a video track that is a composite of one or more video tracks and/or special effects, and (2) an audio track that is a composite of one or more audio tracks and/or special effects. It also might include one or more sets of metadata, each of which might include one or more metadata items. The metadata is stored initially in an application data storage along with the a/v presentation.

From the application data storage, the process initially loads (at 705) the a/v presentation for display. In some cases, this loading operation involves a rendering of the audio and video components of the presentation. The process next determines (at 710) whether there is any metadata set associated with the a/v presentation. If not, the process generates (at 715) an empty list for display, and then displays (at 750) this list. This empty list specifies that there is no metadata associated with the a/v presentation for display. After 750, the process ends.

If the process determines (at 710) that there is metadata associated with the a/v presentation, the process selects (at 720) a metadata set. It then determines (at 725) whether the metadata set that it just selected at 720 includes any display rules regarding displaying the selected metadata set. If not, the process writes (at 730) the selected metadata set to the display list, and then transitions to 745, which will be described below. Otherwise, the process determines (at 735) whether the display rule of the selected set prohibits the displaying of all the data in the selected metadata set. If the display rule prohibits the display of all the data in the selected metadata set, the process transitions to 745, which will be described below.

On the other hand, if the display rule specifies that all or part of the metadata set should be displayed, the process transitions to 740. At 740, the process writes the selected metadata set to the display list according to the display rule identified at 725. In other words, at 740, the process writes to the display list the portion of the selected metadata set that this set's display rule designates for displaying. In some embodiments, the display rule for a metadata set can only specify whether the entire metadata set should be displayed or not. Other embodiments, however, allow a metadata set's display rule to specify one or more subsets of a metadata set for display. After 740, the process transitions to 745.

At 745, the process determines whether it has examined all metadata sets of the a/v presentation. If not, the process returns to 720 to select a metadata set of the presentation that it has not yet examined, and then repeats the above-described operations 725-745 for this selected set. When the process determines (at 745) that it has examined all the metadata sets of the digital video presentation, it presents (at 750) the display list, and then ends.

FIG. 8 conceptually illustrates a computer system 800 that can be used to implement some embodiments of the invention. Computer system 800 includes a bus 805, a processor 810, a system memory 815, a read-only memory 820, a permanent storage device 825, input devices 830, and output devices 835. The bus 805 collectively represents all system, peripheral, and chipset buses that communicatively connect the numerous internal devices of the computer system 800. For instance, the bus 805 communicatively connects the processor 810 with the read-only memory 820, the system memory 815, and the permanent storage device 825.

From these various memory units, the processor 810 retrieves instructions to execute and data to process in order to execute the processes of the invention. The read-only-memory (ROM) 820 stores static data and instructions that are needed by the processor 810 and other modules of the computer system.

The permanent storage device 825, on the other hand, is read-and-write memory device. This device is a non-volatile memory unit that stores instruction and data even when the computer system 800 is off. Some embodiments of the invention use a mass-storage device (such as a magnetic or optical disk and its corresponding disk drive) as the permanent storage device 825.

Other embodiments use a removable storage device (such as a floppy disk or Zip® disk, and its corresponding disk drive) as the permanent storage device. Like the permanent storage device 825, the system memory 815 is a read-and-write memory device. However, unlike storage device 825, the system memory is a volatile read-and-write memory, such as a random access memory. The system memory stores some of the instructions and data that the processor needs at runtime. In some embodiments, the invention's processes are stored in the system memory 815, the permanent storage device 825, and/or the read-only memory 820.

The bus 805 also connects to the input and output devices 830 and 835. The input devices enable the user to communicate information and select commands to the computer system. The input devices 830 include alphanumeric keyboards and cursor-controllers. The output devices 835 display images generated by the computer system. For instance, these devices display IC design layouts. The output devices include printers and display devices, such as cathode ray tubes (CRT) or liquid crystal displays (LCD).

Finally, as shown in FIG. 8, bus 805 also couples computer 800 to a network 865 through a network adapter (not shown). In this manner, the computer can be a part of a network of computers (such as a local area network (“LAN”), a wide area network (“WAN”), or an Intranet) or a network of networks (such as the Internet). Any or all of the components of computer system 800 may be used in conjunction with the invention. However, one of ordinary skill in the art would appreciate that any other system configuration may also be used in conjunction with the present invention.

The invention described above provides a coherent, innovative approach for propagating metadata across different stages of the editing pipeline of a video editing application. This approach allows the editing application to maintain the metadata associated with a digital video presentation, and subsequently use this metadata. By allowing different rules for propagating different types of metadata, the invention provides a robust, flexible mechanism that allows an editor to specify different ways of propagating different metadata across different stages of the editing pipeline.

While the invention has been described with reference to numerous specific details, one of ordinary skill in the art will recognize that the invention can be embodied in other specific forms without departing from the spirit of the invention. Thus, one of ordinary skill in the art would understand that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims. 

1. For a video-editing application, a method of exporting a composite video presentation, the method comprising: editing a plurality of different video items to create a composite video presentation having a video portion, a first set of metadata associated with the video portion, and a set of rules for exporting the video portion with the first set of metadata from the video-editing application to a storage; identifying the set of rules for exporting the video portion with the first set of metadata; and exporting the first set of metadata from the video-editing application to the storage with the video portion only when the set of rules specifies that the first set of metadata should be exported with the video portion, wherein the first set of metadata is not exported to the storage with the video portion when the set of rules does not specify that the first set of metadata should be exported with the video portion, wherein said editing, identifying, and exporting are performed by the video-editing application executing on a computer.
 2. The method of claim 1, wherein the first set of metadata includes multiple pieces of metadata, wherein the set of rules includes a rule not to export a piece of the first set of metadata with the video portion.
 3. The method of claim 1, wherein the first set of metadata includes multiple pieces of metadata, wherein the set of rules includes a rule to export a piece of the first set of metadata with the video portion.
 4. The method of claim 1, wherein the identifying comprises determining whether the first set of metadata is associated with the set of rules, wherein the video portion is exported with the first set of metadata from the video-editing application to the storage when a determination is made that the first set of metadata is not associated with the set of rules.
 5. The method of claim 1, wherein the set of rules is a first set of rules, wherein the composite video presentation has a second set of metadata different than the first set of metadata and a second set of rules for exporting the video portion with the second set of metadata from the video-editing application to the storage, wherein the method further comprises: identifying the second set of rules for exporting the video portion with the second set of metadata; and exporting the second set of metadata from the video-editing application to the storage with the video portion only when the second set of rules specifies that the second set of metadata should be exported with the video portion, wherein the second set of metadata is not exported to the storage with the video portion when the second set of rules does not specify that the second set of metadata should be exported with the video portion.
 6. The method of claim 5, wherein the first set of rules associated with the first set of metadata is different than the second set of rules associated with the second set of metadata.
 7. The method of claim 1 further comprising: before identifying the set of rules, determining whether the composite video presentation is associated with any metadata, and only when the composite video presentation is associated with metadata, identifying the set of rules for exporting the video portion with the first set of metadata.
 8. A non-transitory computer readable medium storing a computer program for execution by at least one processor in order to process metadata associated with video in a multi-state video processing system, the computer program comprising sets of instructions for: identifying a set of rules for propagating a set of metadata between two different states in the video processing system, the set of metadata and the set of rules for propagating the set of metadata stored together in a single structure; propagating the video with the metadata set between the two states when the set of rules specifies that the metadata set should be propagated between the two states; and propagating the video without the metadata set between the two states when the set of rules specifies that the metadata should not be propagated between the two states.
 9. The non-transitory computer readable medium of claim 8, wherein the identified set of rules for propagating comprises a set of rules for exporting the metadata set with the video from one storage to another storage.
 10. The non-transitory computer readable medium of claim 9, wherein the metadata set includes multiple pieces of metadata, wherein the identified set of rules includes a rule not to export a piece of the metadata set.
 11. The non-transitory computer readable medium of claim 9, wherein the metadata set includes multiple pieces of metadata, wherein the identified set of rules includes a rule to export a piece of the metadata set.
 12. The non-transitory computer readable medium of claim 9, wherein the computer program further comprises a set of instructions for exporting the set of metadata to the other storage with the video when the set of metadata is not associated with the set of rules for exporting.
 13. The non-transitory computer readable medium of claim 8, wherein the set of rules is a first set of rules for propagating a first metadata set, the computer program further comprising sets of instructions for: identifying a second set of rules different than the first set of rules for propagating a second set of metadata between two different states in the video processing system, the second set of metadata and the second set of rules for propagating the second set of metadata stored in the single structure along with the first set of metadata and the first set of rules; propagating the video with the second set of metadata between the two states when the second set of rules specifies that the second set of metadata should be propagated between the two states; and propagating the video without the second set of metadata between the two states when the second set of rules specifies that the second set of metadata should not be propagated between the two states.
 14. The non-transitory computer readable medium of claim 8, wherein the structure including the set of metadata and the set of rules for propagating the set of metadata is an XML structure.
 15. A non-transitory computer readable medium storing a computer program for execution by at least one processor in order to process a composite video presentation associated with metadata, the computer program comprising sets of instructions for: editing the composite video presentation according to a video editor's specifications by associating a set of metadata with at least a portion of the composite video presentation, said associated set of metadata including a set of rules for exporting the composite video presentation with the set of metadata to a storage; and exporting the composite video presentation by (i) exporting the portion of the composite video presentation with the metadata set to the storage based on the set of rules, and (ii) exporting a remaining portion of the composite video presentation without the metadata set.
 16. The non-transitory computer readable medium of claim 15, wherein the set of metadata is a first set of metadata, the set of rules is a first set of rules, and the portion of the composite video presentation is a first portion of the composite video presentation, wherein the set of instructions for editing the composite video presentation comprises a set of instructions for associating a second set of metadata with a second portion of the composite video presentation, said second set of metadata different from the first set of metadata and including a second set of rules for exporting the second portion of the composite video presentation with the second metadata set to the storage based on the second set of rules.
 17. The non-transitory computer readable medium of claim 15, wherein the computer program further comprises a set of instructions for editing a first video track and a second video track to define the portion of the composite video presentation.
 18. A non-transitory computer readable medium storing a computer program that when executed by at least one processor exports digital video to a storage, the digital video having at least a first set of metadata, said computer program comprising sets of instructions for: determining whether the first set of metadata of the digital video includes an associated set of rules for exporting the first set of metadata to the storage with the digital video; and when the first set of metadata includes a set of associated rules: (i) exporting the first set of metadata to the storage along with the video when the set of rules specifies that the first set of metadata should be exported with the video; and (ii) exporting the video without the first set of metadata when the set of rules specifies that the first set of metadata should not be exported with the video.
 19. The non-transitory computer readable medium of claim 18, wherein the first set of metadata includes multiple pieces of metadata, wherein the set of associated rules includes a rule not to export a piece of the first set of metadata.
 20. The non-transitory computer readable medium of claim 18, wherein the first set of metadata includes multiples pieces of metadata, wherein the set of associated rules includes a rule to export a piece of the first set of metadata.
 21. The non-transitory computer readable medium of claim 18, wherein the computer program further comprises a set of instructions for exporting the first set of metadata to the storage when the first set of metadata does not include a set of associated rules.
 22. The non-transitory computer readable medium of claim 18, wherein the digital video further has a second set of metadata, wherein the computer program further comprises sets of instructions for: a) determining whether the second set of metadata includes an associated set of rules for exporting the second set of metadata to the storage with the digital video; b) when the second set of metadata includes a set of associated rules: (i) exporting the second set of metadata to the storage along with the video when the set of rules associated with the second set of metadata specifies to export the second set of metadata; and (ii) exporting the video without the second set of metadata when the set of rules associated with the second set of metadata specifies to not export the second set of metadata.
 23. The non-transitory computer readable medium of claim 18, wherein the computer program further comprises a set of instructions for: determining, before determining whether the first set of metadata includes an associated set of rules, whether the digital video has associated metadata, and only when the digital video has associated metadata, determining whether the first set of metadata includes the associated set of rules.
 24. A non-transitory computer readable medium storing a computer program for execution by at least one processor in order to process metadata associated with video in a multi-state video processing system, the computer program comprising sets of instructions for: identifying a first set of rules for propagating a first set of metadata between two different states in the video processing system; propagating the video with the first metadata set between the two states when the first set of rules specifies that the first metadata set should be propagated between the two states; propagating the video without the first metadata set between the two states when the first set of rules specifies that the first metadata set should not be propagated between the two states; identifying a second set of rules for propagating a second set of metadata between the two states, wherein the first and second sets of metadata and the first and second sets of rules are stored together in a single structure; propagating the video with the second metadata set between the two states when the second set of rules specifies that the second metadata set should be propagated between the two states; and propagating the video without the second metadata set between the two states when the second set of rules specifies that the second metadata set should not be propagated between the two states, wherein the first set of rules is not the same as the second set of rules, and the first set of metadata is not the same as the second set of metadata.
 25. The non-transitory computer readable medium of claim 24, wherein the structure including the sets of metadata and the sets of rules for propagating the sets of metadata is an XML structure.
 26. A non-transitory computer readable medium storing a computer program for execution by at least one processor in order to process metadata associated with video in a multi-state video processing system, the computer program comprising sets of instructions for: identifying a first set of rules for propagating a set of metadata between a first pair of states in the video processing system; propagating the video with the metadata set between the first pair of states when the first set of rules specifies that the metadata set should be propagated between the first pair of states; propagating the video without the metadata set between the first pair of states when the first set of rules specifies that the metadata set should not be propagated between the first pair of states; identifying a second set of rules for propagating the metadata set between a second pair of states, wherein at least one of the states in the second pair of states is different from both of the states in the first pair of states; propagating the video with the metadata set between the second pair of states when the second set of rules specifies that the metadata set should be propagated between the second pair of states; and propagating the video without the metadata set between the second pair of states when the second set of rules specifies that the metadata set should not be propagated between the second pair of states, wherein the first set of rules is not the same as the second set of rules. 